There were a few assumptions made in the original post that were
probably wrong and most of them have been corrected in later postings.
I've been involved in lighting and perception for 25 years (see
brianhoodlightingdesign.com for more about that) and can offer some
more opinions.

From the original post:
"I would have thought the darker color retains more heat than a clear
canopy" was responded to with-
'The reason canopy tints tend to be blue/green is to reduce IR (not
UV) transmission into the cockpit and it is noticeable when you go
from a tinted canopy to a clear one (as I have done at present) that
direct sun on the face feels hotter. The tint won't significantly
reduce heat buildup from the greenhouse effect from the light
wavelengths that get through.'

This is mostly correct in my view. First, UV filters made of plastic
tend to be clear while glass UV filters are slightly yellow, but this
has more to do with other factors. UV is by definition not a visible
spectrum so there is no reason for tint to affect UV transmission. On
the other hand, sunlight that is absorbed by a dark canopy (down-
converted to heat in the plastic) would then be cooled by cool air (if
present) passing over the canopy so there could be some benefit there,
plus radiant heat (clear canopy) is much more efficient at heating you
than convective (tinted canopy). In my opinion, tinted is better in
this respect.

From the original post:
"The lower light within the cockpit makes reading some instruments
difficult, especially with age modified eyeballs - I can imagine this
to be true, is it a big problem, does it outweigh any benefits?"

I have to disagree with this. I can't think of any case where the
light levels in the cockpit would fall so low as to prevent easy
viewing of the ASI or altimeter. If you use a PDA it will be much more
visible under a tinted canopy because the contrast ratio (contrast
ratio is a much more important factor than total luminance) is so much
less. The ability of the eye to respond to the very different amounts
of light as it is directed first at a diffuse sky dome and then back
to a dim PDA is the difficult visual task here. In my opinion, tinted
is better in this respect.

Finally,
From the original post:
" no definitive answers, only general observations and personal views"
there will be no definitive answers, because in the end very little is
known about light and how it works on a basic level. That light is
photons that go 186,000mps is a nice theory that is popular but is
contradicted by a lot of other known facts. More to the point, the old
theories of how the eye and brain detect and respond to light via rods
and cones has been quite upset by the research into non-visual
photoreceptors or 'Intrinsically photoreceptive retinal ganglion
cells'. If that is of any interest google 'melanopsin' and go from
there. It's all quite fascinating really, and some of it relates
directly to this question.

Brian





On Jul 30, 3:46 pm, bagmaker
wrote:
Hi all

This has been thrashed out before but a search didnt come up with any
difinitive answers, only general observations and personal views.

What opinions have you all on canopy tinting - what color and why?

The tinted canopy looks better from the outside - Yep, I reckon so